Organic light emitting diode display

ABSTRACT

Disclosed is an organic light emitting diode (OLED) display comprising a substrate; an organic light emitting element disposed on the substrate; an encapsulation substrate disposed on the organic light emitting element; and an adhesive layer formed on the substrate, covering the organic light emitting element, and bonding the substrate on which the organic light emitting element is formed with the encapsulation substrate.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and the benefit of Korean PatentApplication No. 10-2011-0056284 filed in the Korean IntellectualProperty Office on Jun. 10, 2011, the entire contents of which areincorporated herein by reference.

BACKGROUND

1. Field

An organic light emitting diode (OLED) display is provided.

2. Description of the Related Technology

Since an organic light emitting diode (OLED) display has light emittingcharacteristic and does not require a separate light source unlike aliquid crystal display (LCD), the thickness and the weight may bereduced. And, since an organic light emitting diode (OLED) displayexhibits high definition characteristics such as low power consumption,high luminance and high reaction speed, and the like, it is spotlightedas the next generation display device for a portable electronic device.

An organic light emitting diode (OLED) display includes a plurality oforganic light emitting elements having a hole injection electrode, anorganic emission layer, and an electron implant electrode. In theorganic emission layer, light emitting is achieved by energy generatedwhen exitons produced by combination of electrons and holes drop fromthe exited state to the ground state, and the organic light emittingdiode (OLED) display forms an image therewith.

However, since the organic emission layer is sensitive to the externalenvironment such as moisture or oxygen, if the organic emission layer isexposed to moisture and oxygen, quality of the organic light emittingdiode (OLED) display may be deteriorated. Therefore, to protect theorganic light emitting element and prevent penetration of moisture oroxygen in the organic emission layer, an encapsulation substrate isbonded on the display substrate on which the organic light emittingelement is formed by an additional sealing process, or a protectionlayer with a thin thickness is formed on the organic light emittingelement.

However, if an encapsulation substrate is used or a protection layer isformed, to completely prevent penetration of moisture or oxygen in theorganic emission layer, the manufacturing process of the organic lightemitting diode (OLED) display may become complicated and simultaneously,it is difficult to form the organic light emitting diode (OLED) displaywith a thin thickness.

SUMMARY OF CERTAIN INVENTIVE ASPECTS

One embodiment provides an organic light emitting diode (OLED) displaythat may effectively suppress moisture or oxygen penetration, may bemanufactured by a simple process, and has improved yield.

Another embodiment provides a method for manufacturing the organic lightemitting diode (OLED) display.

According to one embodiment, an organic light emitting diode (OLED)display is provided that includes a substrate; an organic light emittingelement disposed on the substrate; an encapsulation substrate disposedon the organic light emitting element; and an adhesive layer formed onthe substrate, covering the organic light emitting element, and bondingthe substrate on which the organic light emitting element is formed withthe encapsulation substrate,

The adhesive layer is formed by sequentially accumulating a firstfilling adhesive layer, a hygroscopic adhesive layer and a secondfilling adhesive layer.

The hygroscopic adhesive layer may include at least one hygroscopicmaterial selected from the group consisting of a silica gel (SiO₂. H₂O),alumino-silicate beads, montmorillonite, molecular sieve of zeolite(Na₁₂AlO₃SiO₂.12H₂O), activated carbon, alkali metal oxide, alkalineearth metal oxide, metal sulfate, metal halide, and metal perchlorate.

The first filling adhesive layer and the second filling adhesive layermay independently include at least one filling material selected fromthe group consisting of talc, silica, magnesium oxide, mica,montmorillonite, alumina, graphite, beryllia (beryllium oxide), aluminumnitride, silicon carbide, mullite and silicon.

The hygroscopic material may have a particle diameter of about 10 nm toabout 20 μm.

The filling material may have a particle diameter of about 10 nm toabout 20 μm.

The hygroscopic material or the filling material may be mesoporous,plate-shaped, spherical, rod-shaped, fiber-shaped, or core-shell typed.

The adhesive layer may include thermally curable resin or photocurableresin.

The first filling adhesive layer, the hygroscopic adhesive layer and thesecond filling adhesive layer may include the same kind of thermallycurable resin or photocurable resin so that the adhesive layer may beformed as one integrated sheet without forming an interface between thelayers.

The first filling adhesive layer and the second filling adhesive layermay independently include about 100 parts by weight of thermally curableresin or photocurable resin; and about 5 to 50 parts by weight offilling material.

The hygroscopic adhesive layer may include about 100 parts by weight ofthermally curable resin or photocurable resin; and about 5 to 50 partsby weight of hygroscopic material.

The adhesive layer may have a thickness of about 5 μm to about 30 μm.

In the adhesive layer, thickness ratio of the first filling adhesivelayer, hygroscopic adhesive layer and the second filling adhesive layermay be about 0.1 to about 1.2:about 0.1 to about 1.2:about 0.1 to about1.2.

According to another embodiment, a method for manufacturing an organiclight emitting diode (OLED) display is provided that includes forming anorganic light emitting element on a substrate; sequentially accumulatinga first filling adhesive layer, a hygroscopic adhesive layer and asecond filling adhesive layer so as to form an adhesive layer; andintervening an adhesive layer between the substrate on which the organiclight emitting element is formed and an encapsulation substrate so as tobond them.

The manufacturing method of the organic light emitting diode (OLED)display may include forming an adhesive layer wherein the first fillingadhesive layer, hygroscopic adhesive layer and the second fillingadhesive layer are sequentially accumulated by a roll to roll process, aroll to glass process, a press process or a diaphragm process.

In the manufacturing method of the organic light emitting diode (OLED)display, after forming the adhesive layer on the encapsulationsubstrate, bonding with the substrate on which the organic lightemitting element is formed may be carried out by a lamination process, apress process or a diaphragm process.

The organic light emitting diode (OLED) display has excellent life-spancharacteristic.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically shows the cross-section of an organic lightemitting diode (OLED) display according to one embodiment.

FIG. 2 schematically shows a manufacturing method of an adhesive layerthat may be included in an organic light emitting diode (OLED) displayaccording to another embodiment.

FIG. 3 schematically shows a cross-section of an organic light emittingdiode (OLED) display according to yet another embodiment.

DETAILED DESCRIPTION OF CERTAIN INVENTIVE EMBODIMENTS

The present embodiments will be described more fully hereinafter withreference to the accompanying drawings, in which example embodiments areshown. As those skilled in the art would realize, the describedembodiments may be modified in various different ways, all withoutdeparting from the spirit or scope of the present embodiments.

A part having no relationship with the description is omitted forclarity, and the same or similar constituent element is indicated by thesame reference numeral throughout the specification.

The size and thickness of each constituent element as shown in thedrawings are randomly indicated for better understanding and ease ofdescription.

The size and thickness of each constituent element as shown in thedrawings are exaggeratedly indicated for better understanding and easeof description.

In the drawings, the thickness of layers, films, panels, regions, etc.,are exaggerated for clarity. In the drawings, the thicknesses of somelayers and regions are exaggerated for better understanding and ease ofdescription. It will be understood that when an element such as a layer,film, region, or substrate is referred to as being “on” another element,it can be directly on the other element or intervening elements may alsobe present. In contrast, when an element is referred to as being“directly on” another element, there are no intervening elementspresent.

Hereinafter, an example embodiment is described referring to FIGS. 1 to3.

FIG. 1 is a cross-sectional view of an organic light emitting diode(OLED) display 100 according to one embodiment.

Referring to FIG. 1, the organic light emitting diode (OLED) display 100includes a substrate 10, an organic light emitting element 20 disposedon the substrate 10, an encapsulation substrate 40 disposed on theorganic light emitting element 20, and an adhesive layer 30 interveningbetween the substrate 10 and the encapsulation substrate 40.

The organic light emitting element 20 has an organic emission layer (notshown) which emits light, displays an image, and is driven by a drivingcircuit part (DC) (shown in FIG. 3). The structures of the organic lightemitting element 20 and the driving circuit part (DC) are not limited tothe structures as shown in FIG. 3, and they may be formed in variousstructures within a range that may be easily modified by a person havingordinary knowledge in the art.

To suppress moisture or oxygen penetration in the organic emissionlayer, the upper part of the organic light emitting element 20 is sealedwith an encapsulation substrate 40 with an intervening adhesive layer 30

Specifically, on the substrate 10 on which the organic light emittingelement 20 is formed, an adhesive layer 30 is formed so as to cover theorganic light emitting element 20, and an encapsulation substrate 40 isformed thereon.

The encapsulation substrate 40 may include an insulator of a glasssubstrate or a plastic substrate, and the like, and if the encapsulationsubstrate comprises transparent material, the display may be used fortop emission.

The adhesive layer 30 is formed by sequentially accumulating a firstfilling adhesive layer 31, a hygroscopic adhesive layer 32 and a secondfilling adhesive layer 33. The first filling adhesive layer 31 and thesecond filling adhesive layer 33 include filling material, and thehygroscopic adhesive layer 32 includes hygroscopic material.

Since the adhesive layer 30 bonds the substrate 10 on which the organiclight emitting element 20 is formed with the encapsulation substrate 40and simultaneously includes hygroscopic material havinghygroscopic/adsorption characteristic and filling material that mayblock moisture incorporated from outside due to barrier characteristicto external moisture, it may protect the organic light emitting element20 from moisture to improve life-span.

The first filling adhesive layer 31, hygroscopic adhesive layer 32 orthe second filling adhesive layer 33 may be manufactured from acomposition mixing filling material or hygroscopic material withthermally curable resin or photocurable resin. The composition isdescribed later.

If the first filling adhesive layer 31, hygroscopic adhesive layer 32and the second filling adhesive layer 33 are all manufactured from acomposition including the same kind of thermally curable resin orphotocurable resin, the adhesive layer 30 may be formed as oneintegrated sheet without forming an interface of the first fillingadhesive layer 31, hygroscopic adhesive layer 32 and the second fillingadhesive layer 33.

The hygroscopic material that may be included in the hygroscopicadhesive layer 32 may include any getter material that may easily reactwith moisture and active gas such as oxygen so that the active gas maynot damage the organic light emitting element 20. For example, a kind ofwater-removing getter material, a drying agent may be used. Thehygroscopic material may be a particle or a medium that may absorb andadsorb moisture and oxygen, and it may include any material capable ofabsorbing and adsorbing moisture and oxygen without limitations.

The hygroscopic material may include, for example, a clay such as silicagel (SiO₂.H₂O), alumino-silicate beads, montmorillonite, and the like, amolecular sieve of zeolite (Na₁₂AlO₃SiO₂.12H₂O), activated carbon,alkali metal oxide, alkaline earth metal oxide, metal sulfate, metalhalide, and metal perchlorate, and a combination thereof.

The alkali metal oxide may include lithium oxide (Li₂O), sodium oxide(Na₂O) or potassium oxide (K₂O); the alkaline earth metal oxide mayinclude barium oxide (BaO), calcium oxide (CaO), magnesium oxide (MgO),and the like, the metal sulfate may include lithium sulfate (Li₂SO₄),sodium sulfate (Na₂SO₄), calcium sulfate (CaSO₄), magnesium sulfate(MgSO₄), cobalt sulfate (CoSO₄), gallium sulfate (Ga₂(SO₄)₃), titaniumsulfate (Ti(SO₄)₂), nickel sulfate (NiSO₄), and the like; the metalhalide may include calcium chloride (CaCl₂), magnesium chloride (MgCl₂),strontium chloride (SrCl₂), yttrium chloride (YCl₃), copper chloride(CuCl₂), cesium fluoride (CsF), tantalum fluoride (TaF₅), niobiumfluoride (NbF₅), lithium bromide (LiBr), calcium bromide (CaBr₂), ceriumbromide (CeBr₃), selenium bromide (SeBr₄), vanadium bromide (VBr₃),magnesium bromide (MgBr₂), barium iodide (BaI₂), magnesium iodide(MgI₂), and the like, the metal perchlorate may include bariumperchlorate (Ba(ClO₄)₂), magnesium perchlorate (Mg(ClO₄)₂), and thelike, but are not limited thereto.

The silica gel is amorphous silica prepared from sodium silicate andsulfuric acid, which exhibits excellent adsorption amount of about 40wt% based on the weight of water, has large adsorption capacity at about25° C. or less and decreased adsorption capacity similar to clay astemperature increases, is non-toxic, noncorrosive, non-deliquescent, andwater-insoluble, may be easily handled, is inexpensive, and does notcause pollution problem, and thus is most widely used.

The montmorillonite is an adsorbent commonly in the form of beadsprepared by drying natural product of magnesium aluminum silicate in theform of subbentonite, which is most inexpensive although it is easilypowderized and thus may cause pollution, and has inferior adsorptioncapacity compared to silica gel.

Since the zeolite has a micro-sphere structure of a net crystalstructure and has very large specific surface area of about 700 to about800 m² per gram, it does not release moisture in the product in thepackaging as temperature rises like silica gel or clay, but it isrelatively expensive.

The activated carbon has very large specific surface area of about 200to about 1200 m² per gram and thus has excellent adsorption capacity,but it may cause pollution and thus is scarcely used as a desiccant fora common use.

Among the alkaline earth metal oxide, calcium oxide is a lime of acalcinated or recalcinated type having moisture adsorption capacity ofabout 28.5 wt % or less, and it is mainly used for dehumidifying foodpackaging of chilled or frozen foods because it has moisture adsorptioncapacity even at very low relative humidity

Among the metal sulfate, calcium sulfate is commercially known asDrierite, is prepared by dehydrating plaster, is chemically stable, isnon-disintegrable, non-toxic and non-corrosive, and does not releaseadsorbed moisture even if temperature rises, but it has low moistureadsorption capacity of about 10 wt % and thus is used within a limitedrange.

The filling material that may be used in the first filling adhesivelayer 31 and the second filling adhesive layer 33 realizes barriercharacteristic to moisture. It is not specifically limited as long as itmay act as a filler having barrier characteristic in the adhesive layer30 of filling material, and specific examples thereof may include talc,silica, magnesium oxide, mica, montmorillonite, alumina, graphite,beryllia (beryllium oxide), aluminum nitride, silicon carbide, mullite,silicon, and a combination thereof, but are not limited thereto. Thefilling material may be a particle prepared by synthesis or it may be aparticle prepared by processing gemstone.

The filling material included in a resin composition for the fillingadhesive layer of the first filling adhesive layer 31 and the secondfilling adhesive layer 33 is uniformly dispersed in the compositionafter curing, and thus, it may distribute stress acting on thecomposition to reinforce adhesion, and may effectively block moisturepenetrated and diffused in the composition so that the moisture may notpass the first filling adhesive layer 31 or the second filling adhesivelayer 33 and be diffused to the organic light emitting element 20.

The hygroscopic material may have a particle diameter of about 10 nm toabout 20 μm. For example, the hygroscopic material may have an averageparticle diameter of about 10 nm to about 100 nm.

The filling material may have a particle diameter of about 10 nm toabout 20 μm. For example, the filling material may have an averageparticle diameter of about 10 nm to about 100 nm. For another example,the filling material may have an average particle diameter of about 2 μmto about 5 μm.

The hygroscopic material or the filling material may be mesoporous,plate-shaped, spherical, rod-shaped, fiber-shaped, core-shell typed, andthe like, but is not limited thereto.

The first filling adhesive layer 31 or the second filling adhesive layer33 may include 5 to 50 parts by weight of the filling material, based on100 parts by weight of the thermosetting resin or photocurable resin.When the filling material is included in the content of about 5 to about50 parts by weight based on 100 parts by weight of the thermosettingresin or photocurable resin, barrier characteristic to moisturepenetration may be improved.

The hygroscopic adhesive layer 32 may include about 5 to about 50 partsby weight of the hygroscopic material based on 100 parts by weight ofthe thermosetting resin or photocurable resin.

The adhesive layer 30 may have a thickness of about 5 μm to about 50 μm.For example, the adhesive layer 30 may have a thickness of about 10 μm,about 20 μm or about 30 μm. When the thickness of the adhesive layer 30is within the above range, it may not be influenced by surface leveldifference and adhesion property may be secured.

The thickness ratio of the first filling adhesive layer 31, thehygroscopic adhesive layer 32 and the second filling adhesive layer 33may be about 0.1 to about 1.2: about 0.1 to about 1.2: about 0.1 toabout 1.2. For example, each layer may be manufactured in the ratio ofabout 1:1:1. When the thickness ratio is within the above range,adhesion characteristic may be secured without being influenced bysurface level difference.

The organic light emitting diode (OLED) display 100 may improvereliability of the organic light emitting element 20 by including theadhesive layer 30. If the material of the encapsulation substrate is notglass, moisture and the like may be incorporated through a defect partof pin-holes and pores formed by particles, but the hygroscopic adhesivelayer in the adhesive layer 30 may absorb or adsorb the moisture, or thefilling adhesive layer may block the moisture to protect the organiclight emitting element 20.

In general, to protect the organic light emitting element 20 frommoisture incorporated from outside, a getter may be coated on the outerpart, but the organic light emitting diode (OLED) display 100 may bedispensed with it to shorten the process. If a getter forming process isskipped, a getter line may not be formed on the outer part and thusmargin may be secured to reduce bezel.

If the adhesive layer 30 is formed in a sandwich structure of the firstfilling adhesive layer 31, the hygroscopic adhesive layer 32 and thesecond filling adhesive layer 33, the hygroscopic adhesive layer 32 mayeffectively block moisture incorporated from the encapsulation substrate40 to the organic light emitting element 20, and the filling adhesivelayers 31 and 33 may bond to the substrate 10, the organic lightemitting element 20, and the encapsulation substrate 40, and the likewhile maintaining adhesion strength. Namely, the adhesive layer 30 mayeffectively block moisture incorporated to the organic light emittingelement 20 without decreasing adhesion characteristic, to increasereliability of the organic light emitting element 20 and improvelife-span.

The first filling adhesive layer 31, hygroscopic adhesive layer 32 orthe second filling adhesive layer 33 may be manufactured from acomposition including filling material or a composition includinghygroscopic material as explained above, wherein the composition formanufacturing the first filling adhesive layer 31, the hygroscopicadhesive layer 32 and the second filling adhesive layer 33 may includethermally curable resin or photocurable resin. The composition, ifnecessary, may further include additives such as a thermally curingagent, a cure accelerating agent, a coupling agent, a spacer, aphotoacid generator, a radical initiator, or a combination thereof.

If the composition for manufacturing the first filling adhesive layer31, the hygroscopic adhesive layer 32 or the second filling adhesivelayer 33 is prepared as a thermally curable resin composition, it mayinclude hygroscopic material or filling material in addition to athermally curable resin, a thermally curing agent, a cure acceleratingagent, a coupling agent, an antioxidant and solvent.

The thermally curable resin may include epoxy resin. The epoxy resin mayinclude bisphenol-based epoxy, ortho-cresol novolac, multi-functionalepoxy, amine-based epoxy, heterocyclic epoxy, substituted epoxy, andnaphthol-based epoxy, specifically, bisphenol A epoxy resin, bisphenol Fepoxy resin, hydrogenated bisphenol type epoxy resin, alicyclic epoxyresin, aromatic epoxy resin, novolac, dicyclopentadiene type epoxyresin, and a combination thereof. Currently available epoxy resinincludes a bisphenol-based epoxy resin such as EPICLON 830-S, EPICLONEXA-830CRP, EPICLON EXA 850-S, EPICLON EXA-850CRP, and EPICLON EXA-835LY(Dainippon Ink & Chemicals Inc.); EPIKOTE 807, EPIKOTE 815, EPIKOTE 825,EPIKOTE827 EPIKOTE 828, EPIKOTE 834, EPIKOTE 1001, EPIKOTE 1004, EPIKOTE1007, and EPIKOTE 1009 (Yuka Shell Epoxy Co.) DER-330, DER-301, DER-361(DOW Chemical Company), YD-128, YDF-170, and the like (KUKDO CHEMICALCO. LTD.); an ortho-cresol novolac-based epoxy resin such asYDCN-500-1P, YDCN-500-4P, YDCN-500-5P, YDCN-500-7P, YDCN-500-80P,YDCN-500-90P (KUKDO CHEMICAL CO. LTD.), EOCN-102S, EOCN-103S, EOCN-104S,EOCN-1012, EOCN-1025, EOCN-1027, and the like (Nippon Kayaku Co. Ltd.);a multi-functional epoxy resin such as Epon 1031 S (Yuka Shell EpoxyCo.), ALALDITE 0163 (Ciba Specialty Chemicals Corp.), DENACOL EX-611,DENACOL EX-614, DENACOL EX-614B, DENACOL EX-622, DENACOL EX-512, DENACOLEX-521, DENACOL EX-421, DENACOL EX-411, DENACOL EX-321, and the like(Nagase ChemteX Corporation); an amine-based epoxy resin such as EPIKOTE604 (Yuka Shell Epoxy Co.), YH-434 (KUKDO CHEMICAL CO. LTD.), TETRAD-X,TETRAD-C (Mitsubishi Gas Chemical Company, Inc.), ELM-120 (SumitomoChemical Co., Ltd.), and the like, a heterocyclic epoxy resin such asPT-810 (Ciba Specialty Chemicals Corp.); a substituted epoxy resin suchas ERL-4234, ERL-4299, ERL-4221, ERL-4206 (Union Carbide Corp.) and anaphthol-based epoxy resin such as EPICLON HP-4032, EPICLON HP-4032D,EPICLON HP-4700, EPICLON 4701 (Dainippon Ink & Chemicals Inc.). Thesemay be used singularly or as a mixture of two or more. To obtainexcellent film coating characteristic, a phenoxy resin may be applied,and a high molecular weight resin such as EPIKOTE 1256 (Japan EpoxyResins Co., Ltd.) and PKHH (InChem Co.), YP-70 (KUKDO CHEMICAL CO.LTD.), and the like may be applied.

As the thermally curing agent, commonly used one for thermally curingepoxy resin may be used without specific limitation. Specific examplesof the thermally curing agent include a polyamine-based curing agentsuch as diethylenetriamine, triethylenetetramine,N-aminoethylpiperazine, diamino diphenylmethane, sebacic aciddihydrazide, and the like; an acid anhydride curing agent such asphthalic anhydride, phthalic tetrahydroanhydride, phthalichexahydroanhydride, phthalic methyltetrahydroanhydride, phthalicmethylhexahydroanhydride, methyl nadic anhydride, and the like; aphenolnovolac curing agent; a polymercaptan curing agent such astrioxanetrimethylenemercaptan, and the like; a tertiary third aminecompound such as benzyldimethylamine,2,4,6-tris(dimethylaminomethyl)phenol, and the like; an imidazolecompound such as 2-methylimidazole, 2-ethyl-4-methylimidazole,1-benzyl-2-methylimidazole, and the like. A solid dispersion typepotential curing agent or a potential curing agent encapsulated in amicrocapsule, and the like may be used.

If an amine-based curing agent is used, aliphatic amine, modifiedaliphatic amine, aromaticamine, secondary amine or tertiary amine, andthe like may be used, and for example, benzyldimethylamine,triethanolamine, triethylene tetramine , diethylenetriamine,triethyleneamine, dimethylaminoethanol, tri(dimethylaminomethyl)phenol,and the like may be used, or a curing agent having —OH, —COOH, —SO₃H,—CONH₂, —CONHR (R represents an alkyl group), —CN(CN)NH₂, —SO₃NH₂,—SO₃NHR (R represents an alkyl group) or —SH at the end group may beused. The R may be a C1-C10 alkyl group, for example, a C 1-C10 linearor branch saturated hydrocarbon group, particularly a C1-C4 linear orbranched alkyl group, and in some embodiments, methyl, ethyl, n-propyl,isopropyl, isobutyl, n-butyl, and t-butyl.

The imidazole-based curing agent may include imidazole, isoimidazole,2-methyl imidazole, 2-ethyl-4-methylimidazole, 2,4-dimethylimidazole,butylimidazole, 2-heptadecenyl-4-methylimidazole, 2-methylimidazole,2-undecenylimidazole,1-vinyl-2-methylimidazole, 2-n-heptadecylimidazole,2-undecylimidazole, 2-heptadecylimidazole, 2-phenylimidazole,1-benzyl-2-methylimidazole, 1-propyl-2-methylimidazole,1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole,1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl -2-phenylimidazole,1-guanaminoethyl-2-methylimidazole, an addition product of imidazole andmethylimidazole, an addition product of imidazole and trimellitic acid,2-n-heptadecyl-4-methylimidazole, phenylimidazole, benzylimidazole,2-methyl-4,5-diphenylimidazole, 2,3,5-triphenylimidazole,2-styrylimidazole, 1-(dodecyl benzyl)-2-methylimidazole,2-(2-hydroxyl-4-t-butylphenyl)-4,5-diphenylimidazole,2-(2-methoxyphenyl)-4,5-diphenylimidazole,2-(3-hydroxyphenyl)-4,5-diphenylimidazole,2-(p-dimethyl-aminophenyl)-4,5-diphenylimidazole,2-(2-hydroxyphenyl)-4,5-diphenylimidazole,di(4,5-diphenyl-2-imidazole)-benzene-1,4,2-naphthyl-4,5-diphenylimidazole,1-benzyl-2-methylimidazole, 2-p-methoxystyrylimidazole, and the like.

The acid anhydride curing agent is an epoxy resin, specifically a hybridepoxy resin including siloxane.

The acid anhydride curing agent may include phthalic anhydride, maleicanhydride, trimellitic anhydride, pyromellitic anhydride,hexahydrophthalic anhydride, tetrahydrophthalic anhydride, methylnadicanhydride, nadic anhydride, glutaric anhydride, methylhexahydrophthalicanhydride, methyltetrahydrophthalic anhydride or5-(2,5-dioxotetrahydrol)-3-methyl-3-cyclohexene-1,2-dicarboxylicacidanhydride.

The cure accelerating agent may include a quaternary ammonium salt, aquaternary sulfonium salt, various metal salts, imidazole, tertiaryamine, and the like. Examples of the quaternary ammonium salt includetetra methyl ammonium bromide, tetrabutylammoniumbromide, and the like,examples of the quaternary sulfonium salt include tetra phenylphosphonium bromide, tetrabutylphosphoniumbromide, examples of the metalsalt may include zinc octylate, tin octylate, and the like, examples ofthe imidazole may include 1-benzyl-2-methyl imidazole, 1-benzyl-2-phenylimidazole, 2-ethyl-4-methyl imidazole, and the like, and examples of thetertiary amine may include benzyl dimethyl amine, and the like.

The boron-based cure accelerating agent may include phenylboronic acid,4-methylphenylboronic acid, 4-methoxyphenyl boronic acid,4-trifluoromethoxyphenyl boronic acid, 4-tert-butoxyphenyl boronic acid,3-fluoro-4-methoxyphenyl boronic acid, pyridine-triphenylborane,2-ethyl-4-methyl imidazolium tetraphenylborate,1,8-diazabicyclo[5.4.0]undecene-7-tetraphenylborate,1,5-diazabicyclo[4.3.0]nonene-5-tetraphenylborate, lithium triphenyl(n-butyl)borate), and the like, the imidazole-based cure acceleratingagent may include 2-methylimidazole, 2-undecylimidazole,2-heptadecylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole,2-phenyl-4-methylimidazole, 1-benzyl-2-phenylimidazole,1,2-dimethylimidazole, 1-cyanoethyl-2-methylimidazole,1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-undecylimidazole,1-cyanoethyl-2-phenylimidazole,1-cyanoethyl-2-undecylimidazolium-trimellitate,1-cyanoethyl-2-phenylimidazolium-trimellitate,2,4-diamino-6-[2′-methylimidazoly-1′]-ethyl-s-triazine,2,4-diamino-6-[2′-undecylimidazoly-11-ethyl-s-triazine,2,4-diamino-6-[2′-ethyl-4′-methylimidazoly-1′]-ethyl-s-triazine,2,4-diamino-6-[2′-methylimidazoly-1′]-ethyl-s-triazine isocyanuric acidadduct dihydrate, a 2-phenylimidazole isocyanuric acid adduct,2-methylimidazole isocyanuric acid adduct dihydrate,2-phenyl-4,5-dihydroxymethylimidazole,2-phenyl-4-methyl-5-hydroxymethylimidazole,2,3-dihyro-1H-pyrrolo[1,2-a]benzimidazole, 4,4′-methylene bis(2-ethyl-5-methylimidazole), 2-methylimidazoline, 2-phenylimidazoline,2,4-diamino-6-vinyl-1,3,5-triazine, a2,4-diarnino-6-vinyl-1,3,5-triazine isocyanuric acid adduct, a2,4-diamino-6-methacryloyloxylethyl-1,3,5-triazineisocyanuric acidadduct, 1-(2-cyanoethyl)-2-ethyl-4-methylimidazole,1-cyanoethyl-2-methylimidazole,1-(2-cyanoethyl)2-phenyl-4,5-di-(cyanoethoxymethyl)imidazole,1-acetyl-2-phenylhydrazine, 2-ethyl-4-methylimidazoline,2-benzyl-4-methyl dimidazoline, 2-ethyl imidazoline, 2-phenyl imidazole,2-phenyl-4,5-dihydroxymethylimidazole, melamine, dicyandiamide, and thelike, and this boron-based cure accelerating agent may be usedsingularly or as a mixture of two or more.

The coupling agent may include a silane coupling agent, a titanate-basedcoupling agent, an aluminate-based coupling agent, a silicon compound,and the like, and the coupling agent may be used singularly or as amixture thereof. The coupling agent may improve adhesion of a resincomposition and decrease viscosity, and it may be included in an amountof about 0.001 to about 5 parts by weight, for example, about 0.01 toabout 3 parts by weight, based on 100 parts by weight of thethermosetting resin in the thermosetting resin composition.

The silane coupling agent functions as an adhesion improving agent forimproving adhesion between the surface of inorganic material such assilica and a resin in the composition. The silane coupling agent mayinclude epoxy containing silane or mercapto containing silane, and thelike, wherein the epoxy containing silane may include 2-(3,4 epoxy cyclohexyl)-ethyltrimethoxysilane, 3-glycidoxytrimethoxysilane,3-glycidoxypropyltriethoxysilane, 3-glycidoxypropyltriethoxysilane, anamine group containing silane may includeN-2(aminoethyl)3-aminopropylmethyldimethoxysilane,N-2(aminoethyl)3-aminopropyltrimethoxysilane,N-2(aminoethyl)3-aminopropyltriethoxysilane,3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane,3-triethoxysily-N-(1,3-dimethylbutylidene)propylamine,N-phenyl-3-aminopropyltrimethoxysilane, the mercapto containing silanemay include 3-mercaptopropylmethyldimethoxysilane,3-mercaptopropyltriethoxysilane, and an isocyanate containing silane mayinclude 3-isocyanatepropyltriethoxysilane, and the silane coupling agentmay be used singularly or as a mixture thereof.

The antioxidant may prevent oxidation degradation during thermal curingof the thermosetting resin composition, thereby further improvingthermal stability of the cured product. The antioxidant may include aphenol based antioxidant, a sulfur based antioxidant, a phosphorousbased antioxidant, and the like. The phenol based antioxidant mayinclude dibutyl hydroxy toluene, 2,6-di-tetra-butyl-p-cresol(hereinafter, referred to as BHT), and the like, the sulfur basedantioxidant may include mercapto propionic acid derivative, and thelike, the phosphorous based antioxidant may include triphenylphosphite,9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (hereinafter, HCA),and the like, and the antioxidant may be used singularly or as a mixturethereof. And, it may be included in an amount of about 0.001 to about 5parts by weight, for example about 0.01 to about 0.5 parts by weight,based on 100 parts by weight of the thermosetting resin in thethermosetting resin composition.

If the composition for manufacturing the first filling adhesive layer31, the hygroscopic adhesive layer 32, or the second filling adhesivelayer 33 is prepared as a photocuarble resin composition, it may includea filling material or a hygroscopic material in addition to aphotocurable epoxy resin, a photoinitiator, a coupling agent, a spacer,a photoacid generator, a radical generator and a solvent.

The photocurable epoxy resin that may be applied for the photocurableresin composition may include a commonly used aromatic epoxy resin, analicyclic epoxy resin, and a mixture thereof The aromatic epoxy resinmay include a biphenyl type, bisphenol A type, bisphenol F type, phenolnovolac, dicyclopentadiene epoxy resin, and the like, and a mixturethereof.

The photoinitiator is not specifically limited as long as it mayphotocure the epoxy resin. The photoinitiator may include an aromaticdiazonium salt, an aromatic sulfonium salt, an aromatic iodine aluminumsalt, an aromatic sulfonium aluminum salt, a metallocene compound and aniron complex salt. For example, an aromatic sulfonium salt may be used,and specific examples thereof may include an aromatic sulfoniumhexafluoro phosphate compound, an aromatic sulfonium hexafluoroantimonate compound, and the like.

As the coupling agent, a silane-based or a titan-based coupling agent,and a silicon compound may be used alone or in combination. For example,a silane coupling agent containing alkoxysilane and diglycidylether inone molecule may be used.

The spacer is not specifically limited as long as it may constantlymaintain the thickness of a panel after curing, and particularly, aspacer capable of maintaining the thickness of a panel about 5 to about50 μm, for example about 5 to about 25 μm may be used. The spacer mayhave a spherical shape, a log shape, and the like, and the shape of thespacer is not specifically limited as long as it may constantly maintainthe thickness of a panel.

The photoacid generator is not specifically limited as long as it mayproduce Lewis acid or Bronsted acid by exposure, and a sulfide saltbased compound such as organic sulfonic acid, and onium based compoundsuch as onium salt may be used. More specific examples includephthimidotrifluoromethanesulfonate, dinitrobenzyltosylate,n-decyldisulfone, naphthylimidotrifluoromethanesulfonate, diphenyliodide, hexafluorophosphate, diphenyl iodide, hexafluoroarsenate,diphenyl iodide, hexafluoroantimonate,diphenylparamethoxyphenylsulfonium triflate,diphenylparatoluenylsulfonium triflate,diphenylparaisobutylphenylsulfonium triflate, triphenylsulfoniumhexafluoro arsenate, triphenylsulfonium hexafluoro antimonate,triphenylsulfonium triflate, dibutylnaphthylsulfonium triflate, and amixture thereof

The radical initiator may be used together with the photoacid generator,and it may include a radical photopolymerization initiator that isdecomposed by electromagnetic energy ray such as UV ray therebyproducing a radical, and a thermally degradable radical polymerizationinitiator that is decomposed by heat to produce a radical. The radicalphotopolymerization initiator may include a type I alpha cleavageinitiator such as an acetophenone derivative such as2-hydroxy-2-methylpropinophenone and 1-hydroxycyclohexyl phenyl ketone;an acylphosphine oxide derivative such asbis(2,4,6-trimethylbenzoyl)phenylphosphine oxide; a benzoin etherderivative such as benzoin methyl ether and benzoin ethyl ether, and thelike. Representative examples of a commercially available radicalphotoinitiator may include IRGACURE 651, IRGACURE 184, IRGACURE 907,DAROCUR 1173 and IRGACURE 819 (Ciba Specialty Chemicals corp.)

A type II photoinitiator may be also used, and the examples may includea compound such as benzophenone, isopropylthioxanthone andanthraquinone. Variously substituted derivatives of the basic compoundsmay also be used. The thermally decomposable radical polymerizationinitiator may include peroxides such as1,1,3,3-tetramethylbutylperoxy-2-ethyl-hexanoate,1,1-bis(t-butylperoxy)cyclohexane, 1,1-bis(t-butylperoxy)cyclo-dodecane, di-t-butylperoxyisophthalate,t-butylperoxybenzoate, dicumylperoxide, t-butylcumylperoxide,2,5-dimethyl-2,5-di(t-butylperoxy)hexane,2,5-dimethyl-2,5-di(t-butylperoxy)-3-hexyne, and cumene hydroperoxide.The radical polymerization initiator may be included in an effectiveamount, for example, about 0.01 to about 5 parts by weight based on 100parts by weight of the photocurable resin in the photocurable resincomposition.

The solvent that may be used in the composition for manufacturing thefirst filling adhesive layer 31, hygroscopic adhesive layer 32 or thesecond filling adhesive layer 33 may include methylethylketone (MEK),tetrahydrofuran (THF), toluene, and the like, it is not specificallylimited as long as it may form a solution for forming a film, and it maybe used alone or in a mixture of two or more kinds to obtain excellentfilm characteristic.

The compositions for manufacturing the first filling adhesive layer 31,hygroscopic adhesive layer 32 and the second filling adhesive layer 33are respectively coated on substrate films 111 and 112, dried and formedas a sheet, and then, stacked to manufacture an adhesive layer 30. Themanufacturing method is not specifically limited and the adhesive layermay be variously manufactured. If characteristic may be embodied byforming a sheet, it may be manufactured as non-cured gel, or asolid-phase, or it may be manufactured as liquid and post-treated.

A method of stacking manufactured hygroscopic adhesive sheet and fillingsheet to form an adhesive layer may be conducted according to a commonlyknown method without specific limitation. For example, a hygroscopicadhesive sheet, a filling adhesive sheet and a hygroscopic adhesivesheet may be sequentially accumulated by a roll to roll process, a rollto glass process, a press process, or a diaphragm process to manufacturean adhesive layer 30 so that each sheet may form a hygroscopic adhesivelayer or a filling adhesive layer

FIG. 2 is a schematic view showing a method of forming an adhesive layer130 according to another embodiment. First, a composition for forming ahygroscopic adhesive layer that includes hygroscopic material is coatedon a substrate film 111 to form a hygroscopic adhesive sheet. On theother hand, a composition for forming a filling adhesive layer thatincludes filling material is coated on another substrate film 112 toform a filling adhesive sheet. The prepared hygroscopic adhesive sheetand filling adhesive sheet are stacked. The stacked hygroscopic adhesivesheet and filling adhesive sheet are bonded by a roll to roll process, aroll to glass process, a press process, or a diaphragm process tomanufacture an adhesive layer 130.

As such, process advantage and structural advantage may be obtained byusing the adhesive layer 130 as one integral sheet.

FIG. 3 is a cross-sectional view of an organic light emitting diode(OLED) display 200 manufactured using the adhesive layer 130manufactured as shown in FIG. 2.

In the organic light emitting diode (OLED) display 200 of FIG. 3, adriving circuit part (DC) and an organic light emitting element 120 areformed on a substrate 110. The driving circuit part (DC) drives theorganic light emitting element 120. The structures of the organic lightemitting element 120 and the driving circuit part (DC) are not limitedas shown in FIG. 3, and they may be formed in various structures withinthe range that may be modified by a person having ordinary knowledge inthe art according to a direction where the organic light emittingelement 120 emits light and displays an image. For example, the adhesivelayer 130 may be manufactured by forming on a TFT substrate. Thesubstrate 110 on which the organic light emitting element 120 is formedand the encapsulation substrate 140 are bonded using the adhesive layer130 manufactured as shown in FIG. 2. The bonding may be conducted bycommonly known methods without specific limitation, and for example, alamination process, a press process or a diaphragm process, and the likemay be used.

According to yet another embodiment, a method for manufacturing anorganic light emitting diode (OLED) display is provided that includesforming an organic light emitting element on a substrate; sequentiallyaccumulating a first filling adhesive layer, a hygroscopic adhesivelayer and a second filling adhesive layer so as to form an adhesivelayer; and, intervening an adhesive layer between the substrate on whichthe organic light emitting element is formed and an encapsulationsubstrate so as to bond them.

The following examples illustrate the present embodiments in moredetail. These examples, however, are not in any sense to be interpretedas limiting the scope of the present embodiments.

EXAMPLE Example 1

About 30 parts by weight of epoxy resin EXA-835LV (Dainippon Ink &Chemicals Inc.), about 45 parts by weight of a phenoxy resinEPIKOTE-1256 (Japan Epoxy Resins Co. Ltd.), about 5 parts by weight of athermally curing agent C11Z-CNS (Shikoku Chemicals Corp.), about 20parts by weight of CaO (UBE Industries, Ltd.) (particle diameter: about1 to 2 μm), and about 100 parts by weight of an organic solvent MEK weremixed to prepare a composition for a hygroscopic adhesive layer, andthen, the composition was coated on a PET substrate film to a thicknessof about 20 μm to manufacture a hygroscopic adhesive sheet.

On the other hand, about 30 parts by weight of epoxy resin EXA-835LV(Dainippon Ink & Chemicals Inc.), about 45 parts by weight of a phenoxyresin EPIKOTE-1256 (Japan Epoxy Resins Co. Ltd.), about 5 parts byweight of a thermally curing agent C11Z-CNS (Shikoku Chemicals Corp.),about 15 parts by weight of Talc D-1000 (Nippon Talc Co., Ltd.)(particle diameter: about 1 to 2 μm), a silane coupling agent KBM-403(Shinetsu), and about 100 parts by weight of an organic solvent MEK weremixed to prepare a composition for a filling adhesive layer, and then,the composition was coated on a PET substrate film to a thickness ofabout 20 μm to manufacture a filling adhesive sheet.

The hygroscopic adhesive sheet and filling adhesive sheet respectivelyformed on a PET substrate film were stacked and bonded by a laminationprocess, and then, the PET substrate film of the filling adhesive sheetwere removed. On the filling adhesive sheet that is exposed by removingthe PET substrate film, the hygroscopic adhesive sheet was stacked againand bonded by a lamination process to form an adhesive layer stacked inthree layers of hygroscopic adhesive layer-filling adhesivelayer-hygroscopic adhesive layer, and the PET substrate films wereremoved.

On the other hand, an organic light emitting element was formed on aglass substrate, the above manufactured adhesive layer was intervenedbetween the substrate and a glass encapsulation substrate so as to coverthe organic light emitting element, and they were bonded at a pressureof about 60Kpa with a diaphragm to manufacture an organic light emittingdiode (OLED) display.

Example 2

An organic light emitting diode (OLED) display was manufactured by thesame method as Example 1, except that about 25 parts by weight of CaOand about 20 parts by weight of talc were used.

Example 3

An organic light emitting diode (OLED) display was manufactured by thesame method as Example 1, except that about 30 parts by weight of CaOand about 25 parts by weight of talc were used.

Comparative Example 1

The hygroscopic adhesive layer was excluded in Example 1, and anadhesive layer consisting only of a filling adhesive layer wasmanufactured with the same thickness as Example 1, thus manufacturing anorganic light emitting diode (OLED) display.

Experimental Example 1 Life-Span Test

The organic light emitting diode (OLED) displays manufactured inExamples 1 to 3 and Comparative Example 1 were introduced in a chamber(TH-TG_JEIO TECH. CO., Ltd.) of about 85° C. 85% RH (relative humidity),light emitting parts were observed according to time, and a time until ablind spot was generated was measured and described in the followingTable 1.

Experimental Example 2 Water Vapor Transmission Rate

For the film type adhesive layers manufactured in Examples 1 to 3 andComparative Example 1, water vapor transmission rate (WVTR) was measured(measuring instrument: Mocon Inc. permatran3/33ma).

Experimental Example 3 Adhesion Strength

For the adhesive layers manufactured in Examples 1 to 3 and ComparativeExample 1, two specimens were stacked in a cross shape and bonded, andthen, strength for detaching both specimens was measured using UTM(INSTRON, model-5900) thereby measuring adhesion strength.

TABLE 1 Comparative Example 1 Example 2 Example 3 Example 1 WVTR 8 7 510 g/m² Adhesion strength 23 23 23 23 (kgf/cm²) Blind spot 1,756 1,9862,135 856 generation time (hours)

While this disclosure has been described in connection with what ispresently considered to be practical example embodiments, it is to beunderstood that the embodiments are not limited to the disclosedembodiments, but, on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

1. An organic light emitting diode (OLED) display comprising asubstrate; an organic light emitting element disposed on the substrate;an encapsulation substrate disposed on the organic light emittingelement; and an adhesive layer formed on the substrate, covering theorganic light emitting element, and bonding the substrate on which theorganic light emitting element is formed with the encapsulationsubstrate, wherein the adhesive layer is formed by sequentiallyaccumulating a first filling adhesive layer, a hygroscopic adhesivelayer and a second filling adhesive layer.
 2. The organic light emittingdiode (OLED) display of claim 1, wherein the hygroscopic adhesive layerincludes at least one hygroscopic material selected from the groupconsisting of silica gel (SiO₂.H₂O), alumino-silicate beads,montmorillonite, a molecular sieve of zeolite (Na₁₂AlO₃SiO₂.12H₂O),activated carbon, alkali metal oxide, alkaline earth metal oxide, metalsulfate, metal halide and metal perchlorate.
 3. The organic lightemitting diode (OLED) display of claim 1, wherein the first fillingadhesive layer and the second filling adhesive layer independentlyinclude at least one filling material selected from the group consistingof talc, silica, magnesium oxide, mica, montmorillonite, alumina,graphite, beryllia (beryllium oxide), aluminum nitride, silicon carbide,mullite and silicon.
 4. The organic light emitting diode (OLED) displayof claim 2, wherein the filling material or hygroscopic material has aparticle diameter of about 10 nm to about 20 μm.
 5. The organic lightemitting diode (OLED) display of claim 3, wherein the filling materialor hygroscopic material has a particle diameter of about 10 nm to about20 μm.
 6. The organic light emitting diode (OLED) display of claim 2,wherein the hygroscopic material or the filling material is mesoporous,plate-shaped, spherical, rod-shaped, fiber-shaped, or core-shell typed.7. The organic light emitting diode (OLED) display of claim 3, whereinthe hygroscopic material or the filling material is mesoporous,plate-shaped, spherical, rod-shaped, fiber-shaped, or core-shell typed.8. The organic light emitting diode (OLED) display of claim 1, whereinthe adhesive layer includes thermally curable resin or photocurableresin.
 9. The organic light emitting diode (OLED) display of claim 8,wherein the first filling adhesive layer, the hygroscopic adhesive layerand the second filling adhesive layer include the same kind of thermallycurable resin or photocurable resin so that the adhesive layer is formedas one integrated sheet without forming an interface between the layers.10. The organic light emitting diode (OLED) display of claim 8, whereinthe hygroscopic adhesive layer comprises about 100 parts by weight ofthermally curable resin or photocurable resin; and about 5 to about 50parts by weight of hygroscopic material.
 11. The organic light emittingdiode (OLED) display of claim 8, wherein the first filling adhesivelayer and the second filling adhesive layer independently comprise about100 parts by weight of thermally curable resin or photocurable resin;and about 5 to about 50 parts by weight of filling material.
 12. Theorganic light emitting diode (OLED) display of claim 1, wherein theadhesive layer has a thickness of about 5 μm to about 30 μm.
 13. Theorganic light emitting diode (OLED) display of claim 1, wherein in theadhesive layer, the thickness ratio of the first filling adhesive layer,hygroscopic adhesive layer and the second filling adhesive layer isabout 0.1 to about 1.2: about 0.1 to about 1.2: about 0.1 to about 1.2.14. A method for manufacturing an organic light emitting diode (OLED)display comprising forming an organic light emitting element on asubstrate; sequentially accumulating a first filling adhesive layer, ahygroscopic adhesive layer and a second filling adhesive layer so as toform an adhesive layer; and intervening an adhesive layer between thesubstrate on which the organic light emitting element is formed and anencapsulation substrate so as to bond them.
 15. The method of claim 14,wherein the adhesive layer comprising sequentially accumulated firstfilling adhesive layer, hygroscopic adhesive layer and second fillingadhesive layer is formed by a roll to roll process, a roll to glassprocess, a press process or a diaphragm process.
 16. The method of claim14, wherein after forming the adhesive layer on the encapsulationsubstrate, bonding with the substrate on which the organic lightemitting element is formed is carried out by a lamination process, apress process or a diaphragm process.
 17. The method of claim 14,wherein the hygroscopic adhesive layer includes at least one hygroscopicmaterial selected from the group consisting of silica gel (SiO₂.H₂O),alumino-silicate beads, montmorillonite, a molecular sieve of zeolite(Na₁₂AlO₃SiO₂.12H₂O), activated carbon, alkali metal oxide, alkalineearth metal oxide, metal sulfate, metal halide and metal perchlorate.18. The method of claim 14, wherein the first filling adhesive layer andthe second filling adhesive layer independently include at least onefilling material selected from the group consisting of talc, silica,magnesium oxide, mica, montmorillonite, alumina, graphite, beryllia(beryllium oxide), aluminum nitride, silicon carbide, mullite andsilicon.
 19. The method of claim 14, wherein the filling material orhygroscopic material has a particle diameter of about 10 nm to about 20μm.
 20. The method of claim 14, wherein the adhesive layer includesthermally curable resin or photocurable resin.